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<a href="qsem_8c.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/******************************************************************************</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> * qLibc</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> *</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> * Copyright (c) 2010-2015 Seungyoung Kim.</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> * All rights reserved.</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> *</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> * Redistribution and use in source and binary forms, with or without</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> * modification, are permitted provided that the following conditions are met:</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> *</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> * 1. Redistributions of source code must retain the above copyright notice,</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"> *    this list of conditions and the following disclaimer.</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> * 2. Redistributions in binary form must reproduce the above copyright notice,</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> *    this list of conditions and the following disclaimer in the documentation</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> *    and/or other materials provided with the distribution.</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> *</span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS &quot;AS IS&quot;</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"> * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE</span></div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment"> * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment"> * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span><span class="comment"> * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR</span></div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span><span class="comment"> * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF</span></div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span><span class="comment"> * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS</span></div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno">   23</span><span class="comment"> * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN</span></div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno">   24</span><span class="comment"> * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)</span></div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span><span class="comment"> * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE</span></div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span><span class="comment"> * POSSIBILITY OF SUCH DAMAGE.</span></div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno">   27</span><span class="comment"> *****************************************************************************/</span></div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span><span class="comment"></span> </div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span><span class="comment">/**</span></div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span><span class="comment"> * @file qsem.c Semaphore APIs.</span></div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno">   31</span><span class="comment"> *</span></div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno">   32</span><span class="comment"> * @note</span></div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno">   33</span><span class="comment"> * @code</span></div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno">   34</span><span class="comment"> *   [daemon main]</span></div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno">   35</span><span class="comment"> *   #define MAX_SEMAPHORES (2)</span></div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span><span class="comment"> *</span></div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span><span class="comment"> *   // create semaphores</span></div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span><span class="comment"> *   int semid = qsem_init(&quot;/some/file/for/generating/unique/key&quot;, &#39;q&#39;, MAX_SEMAPHORES, true);</span></div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span><span class="comment"> *   if(semid &lt; 0) {</span></div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span><span class="comment"> *     printf(&quot;ERROR: Can&#39;t initialize semaphores.\n&quot;);</span></div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno">   41</span><span class="comment"> *     return -1;</span></div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno">   42</span><span class="comment"> *   }</span></div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span><span class="comment"> *</span></div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span><span class="comment"> *   // fork childs</span></div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span><span class="comment"> *   (... child forking codes ...)</span></div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span><span class="comment"> *</span></div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span><span class="comment"> *   // at the end of daemon, free semaphores</span></div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span><span class="comment"> *   if(semid &gt;= 0) qsem_free(semid);</span></div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span><span class="comment"> *</span></div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span><span class="comment"> *   [forked child]</span></div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span><span class="comment"> *   // critical section for resource 0</span></div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span><span class="comment"> *   qsem_enter(semid, 0);</span></div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span><span class="comment"> *   (... guaranteed as atomic procedure ...)</span></div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span><span class="comment"> *   qsem_leave(semid, 0);</span></div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span><span class="comment"> *</span></div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span><span class="comment"> *   (... some codes ...)</span></div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span><span class="comment"> *</span></div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span><span class="comment"> *   // critical section for resource 1</span></div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span><span class="comment"> *   qsem_enter(semid, 1);</span></div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span><span class="comment"> *   (... guaranteed as atomic procedure ...)</span></div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span><span class="comment"> *   qsem_leave(semid, 1);</span></div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span><span class="comment"> *</span></div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span><span class="comment"> *   [other program which uses resource 1]</span></div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span><span class="comment"> *   int semid = qsem_getid(&quot;/some/file/for/generating/unique/key&quot;, &#39;q&#39;);</span></div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span><span class="comment"> *   if(semid &lt; 0) {</span></div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span><span class="comment"> *     printf(&quot;ERROR: Can&#39;t get semaphore id.\n&quot;);</span></div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno">   67</span><span class="comment"> *     return -1;</span></div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span><span class="comment"> *   }</span></div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span><span class="comment"> *</span></div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span><span class="comment"> *   // critical section for resource 1</span></div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span><span class="comment"> *   qsem_enter(semid, 1);</span></div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span><span class="comment"> *   (... guaranteed as atomic procedure ...)</span></div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span><span class="comment"> *   qsem_leave(semid, 1);</span></div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno">   74</span><span class="comment"> *</span></div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span><span class="comment"> * @endcode</span></div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno">   76</span><span class="comment"> */</span></div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno">   77</span> </div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span><span class="preprocessor">#ifndef DISABLE_IPC</span></div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span> </div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span><span class="preprocessor">#include &lt;stdio.h&gt;</span></div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span><span class="preprocessor">#include &lt;stdlib.h&gt;</span></div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno">   82</span><span class="preprocessor">#include &lt;stdbool.h&gt;</span></div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span><span class="preprocessor">#include &lt;unistd.h&gt;</span></div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span><span class="preprocessor">#include &lt;sys/sem.h&gt;</span></div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span><span class="preprocessor">#include &quot;qinternal.h&quot;</span></div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno">   86</span><span class="preprocessor">#include &quot;ipc/qsem.h&quot;</span></div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span><span class="comment"></span> </div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span><span class="comment">/**</span></div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span><span class="comment"> * Initialize semaphore</span></div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span><span class="comment"> *</span></div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span><span class="comment"> * @param keyfile   seed for generating unique IPC key</span></div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span><span class="comment"> * @param keyid     seed for generating unique IPC key</span></div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span><span class="comment"> * @param nsems     number of semaphores to initialize</span></div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno">   94</span><span class="comment"> * @param recreate set to true to re-create semaphore if exists</span></div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno">   95</span><span class="comment"> *</span></div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno">   96</span><span class="comment"> * @return non-negative shared memory identifier if successful, otherwise returns -1</span></div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span><span class="comment"> *</span></div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno">   98</span><span class="comment"> * @code</span></div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span><span class="comment"> *   int semid = qsem_init(&quot;/tmp/mydaemon.pid&quot;, &#39;q&#39;, 10, true);</span></div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span><span class="comment"> * @endcode</span></div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno">  101</span><span class="comment"> */</span></div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno"><a class="line" href="qsem_8c.html#ac66cb18076dd21f67ac4b9a5b246d2d2">  102</a></span><span class="keywordtype">int</span> <a class="code hl_function" href="qsem_8c.html#ac66cb18076dd21f67ac4b9a5b246d2d2">qsem_init</a>(<span class="keyword">const</span> <span class="keywordtype">char</span> *keyfile, <span class="keywordtype">int</span> keyid, <span class="keywordtype">int</span> nsems, <span class="keywordtype">bool</span> recreate) {</div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span>    key_t semkey;</div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span>    <span class="keywordtype">int</span> semid;</div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span> </div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span>    <span class="comment">// generate unique key using ftok();</span></div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno">  107</span>    <span class="keywordflow">if</span> (keyfile != NULL) {</div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span>        semkey = ftok(keyfile, keyid);</div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span>        <span class="keywordflow">if</span> (semkey == -1)</div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno">  110</span>            <span class="keywordflow">return</span> -1;</div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span>    } <span class="keywordflow">else</span> {</div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span>        semkey = IPC_PRIVATE;</div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno">  113</span>    }</div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span> </div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno">  115</span>    <span class="comment">// create semaphores</span></div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno">  116</span>    <span class="keywordflow">if</span> ((semid = semget(semkey, nsems, IPC_CREAT | IPC_EXCL | 0666)) == -1) {</div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span>        <span class="keywordflow">if</span> (recreate == <span class="keyword">false</span>)</div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span>            <span class="keywordflow">return</span> -1;</div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span> </div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span>        <span class="comment">// destroy &amp; re-create</span></div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno">  121</span>        <span class="keywordflow">if</span> ((semid = <a class="code hl_function" href="qsem_8c.html#aac470476fa8ecdc4cd9ec9596d3d6ca4">qsem_getid</a>(keyfile, keyid)) &gt;= 0)</div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno">  122</span>            <a class="code hl_function" href="qsem_8c.html#ab73d1cc1e7a82ce1b4b119ff56d25011">qsem_free</a>(semid);</div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span>        <span class="keywordflow">if</span> ((semid = semget(semkey, nsems, IPC_CREAT | IPC_EXCL | 0666)) == -1)</div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span>            <span class="keywordflow">return</span> -1;</div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span>    }</div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno">  126</span> </div>
<div class="line"><a id="l00127" name="l00127"></a><span class="lineno">  127</span>    <span class="comment">// initializing</span></div>
<div class="line"><a id="l00128" name="l00128"></a><span class="lineno">  128</span>    <span class="keywordtype">int</span> i;</div>
<div class="line"><a id="l00129" name="l00129"></a><span class="lineno">  129</span>    <span class="keywordflow">for</span> (i = 0; i &lt; nsems; i++) {</div>
<div class="line"><a id="l00130" name="l00130"></a><span class="lineno">  130</span>        <span class="keyword">struct </span>sembuf sbuf;</div>
<div class="line"><a id="l00131" name="l00131"></a><span class="lineno">  131</span> </div>
<div class="line"><a id="l00132" name="l00132"></a><span class="lineno">  132</span>        <span class="comment">/* set sbuf */</span></div>
<div class="line"><a id="l00133" name="l00133"></a><span class="lineno">  133</span>        sbuf.sem_num = i;</div>
<div class="line"><a id="l00134" name="l00134"></a><span class="lineno">  134</span>        sbuf.sem_op = 1;</div>
<div class="line"><a id="l00135" name="l00135"></a><span class="lineno">  135</span>        sbuf.sem_flg = 0;</div>
<div class="line"><a id="l00136" name="l00136"></a><span class="lineno">  136</span> </div>
<div class="line"><a id="l00137" name="l00137"></a><span class="lineno">  137</span>        <span class="comment">/* initialize */</span></div>
<div class="line"><a id="l00138" name="l00138"></a><span class="lineno">  138</span>        <span class="keywordflow">if</span> (semop(semid, &amp;sbuf, 1) != 0) {</div>
<div class="line"><a id="l00139" name="l00139"></a><span class="lineno">  139</span>            <a class="code hl_function" href="qsem_8c.html#ab73d1cc1e7a82ce1b4b119ff56d25011">qsem_free</a>(semid);</div>
<div class="line"><a id="l00140" name="l00140"></a><span class="lineno">  140</span>            <span class="keywordflow">return</span> -1;</div>
<div class="line"><a id="l00141" name="l00141"></a><span class="lineno">  141</span>        }</div>
<div class="line"><a id="l00142" name="l00142"></a><span class="lineno">  142</span>    }</div>
<div class="line"><a id="l00143" name="l00143"></a><span class="lineno">  143</span> </div>
<div class="line"><a id="l00144" name="l00144"></a><span class="lineno">  144</span>    <span class="keywordflow">return</span> semid;</div>
<div class="line"><a id="l00145" name="l00145"></a><span class="lineno">  145</span>}</div>
<div class="line"><a id="l00146" name="l00146"></a><span class="lineno">  146</span><span class="comment"></span> </div>
<div class="line"><a id="l00147" name="l00147"></a><span class="lineno">  147</span><span class="comment">/**</span></div>
<div class="line"><a id="l00148" name="l00148"></a><span class="lineno">  148</span><span class="comment"> * Get semaphore identifier by keyfile and keyid for the existing semaphore</span></div>
<div class="line"><a id="l00149" name="l00149"></a><span class="lineno">  149</span><span class="comment"> *</span></div>
<div class="line"><a id="l00150" name="l00150"></a><span class="lineno">  150</span><span class="comment"> * @param keyfile   seed for generating unique IPC key</span></div>
<div class="line"><a id="l00151" name="l00151"></a><span class="lineno">  151</span><span class="comment"> * @param keyid     seed for generating unique IPC key</span></div>
<div class="line"><a id="l00152" name="l00152"></a><span class="lineno">  152</span><span class="comment"> *</span></div>
<div class="line"><a id="l00153" name="l00153"></a><span class="lineno">  153</span><span class="comment"> * @return non-negative shared memory identifier if successful, otherwise returns -1</span></div>
<div class="line"><a id="l00154" name="l00154"></a><span class="lineno">  154</span><span class="comment"> */</span></div>
<div class="line"><a id="l00155" name="l00155"></a><span class="lineno"><a class="line" href="qsem_8c.html#aac470476fa8ecdc4cd9ec9596d3d6ca4">  155</a></span><span class="keywordtype">int</span> <a class="code hl_function" href="qsem_8c.html#aac470476fa8ecdc4cd9ec9596d3d6ca4">qsem_getid</a>(<span class="keyword">const</span> <span class="keywordtype">char</span> *keyfile, <span class="keywordtype">int</span> keyid) {</div>
<div class="line"><a id="l00156" name="l00156"></a><span class="lineno">  156</span>    <span class="keywordtype">int</span> semid;</div>
<div class="line"><a id="l00157" name="l00157"></a><span class="lineno">  157</span> </div>
<div class="line"><a id="l00158" name="l00158"></a><span class="lineno">  158</span>    <span class="comment">/* generate unique key using ftok() */</span></div>
<div class="line"><a id="l00159" name="l00159"></a><span class="lineno">  159</span>    key_t semkey = ftok(keyfile, keyid);</div>
<div class="line"><a id="l00160" name="l00160"></a><span class="lineno">  160</span>    <span class="keywordflow">if</span> (semkey == -1)</div>
<div class="line"><a id="l00161" name="l00161"></a><span class="lineno">  161</span>        <span class="keywordflow">return</span> -1;</div>
<div class="line"><a id="l00162" name="l00162"></a><span class="lineno">  162</span> </div>
<div class="line"><a id="l00163" name="l00163"></a><span class="lineno">  163</span>    <span class="comment">/* get current semaphore id */</span></div>
<div class="line"><a id="l00164" name="l00164"></a><span class="lineno">  164</span>    <span class="keywordflow">if</span> ((semid = semget(semkey, 0, 0)) == -1)</div>
<div class="line"><a id="l00165" name="l00165"></a><span class="lineno">  165</span>        <span class="keywordflow">return</span> -1;</div>
<div class="line"><a id="l00166" name="l00166"></a><span class="lineno">  166</span> </div>
<div class="line"><a id="l00167" name="l00167"></a><span class="lineno">  167</span>    <span class="keywordflow">return</span> semid;</div>
<div class="line"><a id="l00168" name="l00168"></a><span class="lineno">  168</span>}</div>
<div class="line"><a id="l00169" name="l00169"></a><span class="lineno">  169</span><span class="comment"></span> </div>
<div class="line"><a id="l00170" name="l00170"></a><span class="lineno">  170</span><span class="comment">/**</span></div>
<div class="line"><a id="l00171" name="l00171"></a><span class="lineno">  171</span><span class="comment"> * Turn on the flag of semaphore then entering critical section</span></div>
<div class="line"><a id="l00172" name="l00172"></a><span class="lineno">  172</span><span class="comment"> *</span></div>
<div class="line"><a id="l00173" name="l00173"></a><span class="lineno">  173</span><span class="comment"> * @param semid     semaphore identifier</span></div>
<div class="line"><a id="l00174" name="l00174"></a><span class="lineno">  174</span><span class="comment"> * @param semno     semaphore number</span></div>
<div class="line"><a id="l00175" name="l00175"></a><span class="lineno">  175</span><span class="comment"> *</span></div>
<div class="line"><a id="l00176" name="l00176"></a><span class="lineno">  176</span><span class="comment"> * @return true if successful, otherwise returns false</span></div>
<div class="line"><a id="l00177" name="l00177"></a><span class="lineno">  177</span><span class="comment"> *</span></div>
<div class="line"><a id="l00178" name="l00178"></a><span class="lineno">  178</span><span class="comment"> * @note If the semaphore is already turned on, this will wait until released</span></div>
<div class="line"><a id="l00179" name="l00179"></a><span class="lineno">  179</span><span class="comment"> */</span></div>
<div class="line"><a id="l00180" name="l00180"></a><span class="lineno"><a class="line" href="qsem_8c.html#acd893b0a1a6b390f27621ae0e93a5dd8">  180</a></span><span class="keywordtype">bool</span> <a class="code hl_function" href="qsem_8c.html#acd893b0a1a6b390f27621ae0e93a5dd8">qsem_enter</a>(<span class="keywordtype">int</span> semid, <span class="keywordtype">int</span> semno) {</div>
<div class="line"><a id="l00181" name="l00181"></a><span class="lineno">  181</span>    <span class="keyword">struct </span>sembuf sbuf;</div>
<div class="line"><a id="l00182" name="l00182"></a><span class="lineno">  182</span> </div>
<div class="line"><a id="l00183" name="l00183"></a><span class="lineno">  183</span>    <span class="comment">/* set sbuf */</span></div>
<div class="line"><a id="l00184" name="l00184"></a><span class="lineno">  184</span>    sbuf.sem_num = semno;</div>
<div class="line"><a id="l00185" name="l00185"></a><span class="lineno">  185</span>    sbuf.sem_op = -1;</div>
<div class="line"><a id="l00186" name="l00186"></a><span class="lineno">  186</span>    sbuf.sem_flg = SEM_UNDO;</div>
<div class="line"><a id="l00187" name="l00187"></a><span class="lineno">  187</span> </div>
<div class="line"><a id="l00188" name="l00188"></a><span class="lineno">  188</span>    <span class="comment">/* lock */</span></div>
<div class="line"><a id="l00189" name="l00189"></a><span class="lineno">  189</span>    <span class="keywordflow">if</span> (semop(semid, &amp;sbuf, 1) != 0)</div>
<div class="line"><a id="l00190" name="l00190"></a><span class="lineno">  190</span>        <span class="keywordflow">return</span> <span class="keyword">false</span>;</div>
<div class="line"><a id="l00191" name="l00191"></a><span class="lineno">  191</span>    <span class="keywordflow">return</span> <span class="keyword">true</span>;</div>
<div class="line"><a id="l00192" name="l00192"></a><span class="lineno">  192</span>}</div>
<div class="line"><a id="l00193" name="l00193"></a><span class="lineno">  193</span><span class="comment"></span> </div>
<div class="line"><a id="l00194" name="l00194"></a><span class="lineno">  194</span><span class="comment">/**</span></div>
<div class="line"><a id="l00195" name="l00195"></a><span class="lineno">  195</span><span class="comment"> * Try to turn on the flag of semaphore. If it is already turned on, do not wait.</span></div>
<div class="line"><a id="l00196" name="l00196"></a><span class="lineno">  196</span><span class="comment"> *</span></div>
<div class="line"><a id="l00197" name="l00197"></a><span class="lineno">  197</span><span class="comment"> * @param semid     semaphore identifier</span></div>
<div class="line"><a id="l00198" name="l00198"></a><span class="lineno">  198</span><span class="comment"> * @param semno     semaphore number</span></div>
<div class="line"><a id="l00199" name="l00199"></a><span class="lineno">  199</span><span class="comment"> *</span></div>
<div class="line"><a id="l00200" name="l00200"></a><span class="lineno">  200</span><span class="comment"> * @return true if successful, otherwise(already turned on by other) returns false</span></div>
<div class="line"><a id="l00201" name="l00201"></a><span class="lineno">  201</span><span class="comment"> */</span></div>
<div class="line"><a id="l00202" name="l00202"></a><span class="lineno"><a class="line" href="qsem_8c.html#a5993822d89f9f6f36ffcedf95a921be0">  202</a></span><span class="keywordtype">bool</span> <a class="code hl_function" href="qsem_8c.html#a5993822d89f9f6f36ffcedf95a921be0">qsem_enter_nowait</a>(<span class="keywordtype">int</span> semid, <span class="keywordtype">int</span> semno) {</div>
<div class="line"><a id="l00203" name="l00203"></a><span class="lineno">  203</span>    <span class="keyword">struct </span>sembuf sbuf;</div>
<div class="line"><a id="l00204" name="l00204"></a><span class="lineno">  204</span> </div>
<div class="line"><a id="l00205" name="l00205"></a><span class="lineno">  205</span>    <span class="comment">/* set sbuf */</span></div>
<div class="line"><a id="l00206" name="l00206"></a><span class="lineno">  206</span>    sbuf.sem_num = semno;</div>
<div class="line"><a id="l00207" name="l00207"></a><span class="lineno">  207</span>    sbuf.sem_op = -1;</div>
<div class="line"><a id="l00208" name="l00208"></a><span class="lineno">  208</span>    sbuf.sem_flg = SEM_UNDO | IPC_NOWAIT;</div>
<div class="line"><a id="l00209" name="l00209"></a><span class="lineno">  209</span> </div>
<div class="line"><a id="l00210" name="l00210"></a><span class="lineno">  210</span>    <span class="comment">/* lock */</span></div>
<div class="line"><a id="l00211" name="l00211"></a><span class="lineno">  211</span>    <span class="keywordflow">if</span> (semop(semid, &amp;sbuf, 1) != 0)</div>
<div class="line"><a id="l00212" name="l00212"></a><span class="lineno">  212</span>        <span class="keywordflow">return</span> <span class="keyword">false</span>;</div>
<div class="line"><a id="l00213" name="l00213"></a><span class="lineno">  213</span>    <span class="keywordflow">return</span> <span class="keyword">true</span>;</div>
<div class="line"><a id="l00214" name="l00214"></a><span class="lineno">  214</span>}</div>
<div class="line"><a id="l00215" name="l00215"></a><span class="lineno">  215</span><span class="comment"></span> </div>
<div class="line"><a id="l00216" name="l00216"></a><span class="lineno">  216</span><span class="comment">/**</span></div>
<div class="line"><a id="l00217" name="l00217"></a><span class="lineno">  217</span><span class="comment"> * Force to turn on the flag of semaphore.</span></div>
<div class="line"><a id="l00218" name="l00218"></a><span class="lineno">  218</span><span class="comment"> *</span></div>
<div class="line"><a id="l00219" name="l00219"></a><span class="lineno">  219</span><span class="comment"> * @param semid     semaphore identifier</span></div>
<div class="line"><a id="l00220" name="l00220"></a><span class="lineno">  220</span><span class="comment"> * @param semno     semaphore number</span></div>
<div class="line"><a id="l00221" name="l00221"></a><span class="lineno">  221</span><span class="comment"> * @param maxwaitms maximum waiting micro-seconds to release</span></div>
<div class="line"><a id="l00222" name="l00222"></a><span class="lineno">  222</span><span class="comment"> * @param forceflag status will be stored, it can be NULL if you don&#39;t need this information</span></div>
<div class="line"><a id="l00223" name="l00223"></a><span class="lineno">  223</span><span class="comment"> *</span></div>
<div class="line"><a id="l00224" name="l00224"></a><span class="lineno">  224</span><span class="comment"> * @return true if successful, otherwise returns false</span></div>
<div class="line"><a id="l00225" name="l00225"></a><span class="lineno">  225</span><span class="comment"> *</span></div>
<div class="line"><a id="l00226" name="l00226"></a><span class="lineno">  226</span><span class="comment"> * @note</span></div>
<div class="line"><a id="l00227" name="l00227"></a><span class="lineno">  227</span><span class="comment"> * This will wait the semaphore to be released with in maxwaitms.</span></div>
<div class="line"><a id="l00228" name="l00228"></a><span class="lineno">  228</span><span class="comment"> * If it it released by locker normally with in maxwaitms, forceflag will be set to false.</span></div>
<div class="line"><a id="l00229" name="l00229"></a><span class="lineno">  229</span><span class="comment"> * But if maximum maxwaitms is exceed and the semaphore is released forcely, forceflag will</span></div>
<div class="line"><a id="l00230" name="l00230"></a><span class="lineno">  230</span><span class="comment"> * be set to true.</span></div>
<div class="line"><a id="l00231" name="l00231"></a><span class="lineno">  231</span><span class="comment"> */</span></div>
<div class="line"><a id="l00232" name="l00232"></a><span class="lineno"><a class="line" href="qsem_8c.html#a023df7733cebc81fc0aa0285772a914d">  232</a></span><span class="keywordtype">bool</span> <a class="code hl_function" href="qsem_8c.html#a023df7733cebc81fc0aa0285772a914d">qsem_enter_force</a>(<span class="keywordtype">int</span> semid, <span class="keywordtype">int</span> semno, <span class="keywordtype">int</span> maxwaitms, <span class="keywordtype">bool</span> *forceflag) {</div>
<div class="line"><a id="l00233" name="l00233"></a><span class="lineno">  233</span>    <span class="keywordtype">int</span> wait;</div>
<div class="line"><a id="l00234" name="l00234"></a><span class="lineno">  234</span>    <span class="keywordflow">for</span> (wait = 0; wait &lt; maxwaitms; wait += 10) {</div>
<div class="line"><a id="l00235" name="l00235"></a><span class="lineno">  235</span>        <span class="keywordflow">if</span> (<a class="code hl_function" href="qsem_8c.html#a5993822d89f9f6f36ffcedf95a921be0">qsem_enter_nowait</a>(semid, semno) == <span class="keyword">true</span>) {</div>
<div class="line"><a id="l00236" name="l00236"></a><span class="lineno">  236</span>            <span class="keywordflow">if</span> (forceflag != NULL)</div>
<div class="line"><a id="l00237" name="l00237"></a><span class="lineno">  237</span>                *forceflag = <span class="keyword">false</span>;</div>
<div class="line"><a id="l00238" name="l00238"></a><span class="lineno">  238</span>            <span class="keywordflow">return</span> <span class="keyword">true</span>;</div>
<div class="line"><a id="l00239" name="l00239"></a><span class="lineno">  239</span>        }</div>
<div class="line"><a id="l00240" name="l00240"></a><span class="lineno">  240</span>        usleep(10 * 1000);  <span class="comment">// sleep 10ms</span></div>
<div class="line"><a id="l00241" name="l00241"></a><span class="lineno">  241</span>    }</div>
<div class="line"><a id="l00242" name="l00242"></a><span class="lineno">  242</span> </div>
<div class="line"><a id="l00243" name="l00243"></a><span class="lineno">  243</span>    DEBUG(<span class="stringliteral">&quot;force to unlock semaphore %d-%d&quot;</span>, semid, semno);</div>
<div class="line"><a id="l00244" name="l00244"></a><span class="lineno">  244</span>    <span class="keywordflow">while</span> (<span class="keyword">true</span>) {</div>
<div class="line"><a id="l00245" name="l00245"></a><span class="lineno">  245</span>        <a class="code hl_function" href="qsem_8c.html#a4904a3e477119a2cf177a23068a58fdd">qsem_leave</a>(semid, semno);</div>
<div class="line"><a id="l00246" name="l00246"></a><span class="lineno">  246</span>        <span class="keywordflow">if</span> (<a class="code hl_function" href="qsem_8c.html#a5993822d89f9f6f36ffcedf95a921be0">qsem_enter_nowait</a>(semid, semno) == <span class="keyword">true</span>)</div>
<div class="line"><a id="l00247" name="l00247"></a><span class="lineno">  247</span>            <span class="keywordflow">break</span>;</div>
<div class="line"><a id="l00248" name="l00248"></a><span class="lineno">  248</span>    }</div>
<div class="line"><a id="l00249" name="l00249"></a><span class="lineno">  249</span> </div>
<div class="line"><a id="l00250" name="l00250"></a><span class="lineno">  250</span>    <span class="keywordflow">if</span> (forceflag != NULL)</div>
<div class="line"><a id="l00251" name="l00251"></a><span class="lineno">  251</span>        *forceflag = <span class="keyword">true</span>;</div>
<div class="line"><a id="l00252" name="l00252"></a><span class="lineno">  252</span>    <span class="keywordflow">return</span> <span class="keyword">true</span>;</div>
<div class="line"><a id="l00253" name="l00253"></a><span class="lineno">  253</span>}</div>
<div class="line"><a id="l00254" name="l00254"></a><span class="lineno">  254</span><span class="comment"></span> </div>
<div class="line"><a id="l00255" name="l00255"></a><span class="lineno">  255</span><span class="comment">/**</span></div>
<div class="line"><a id="l00256" name="l00256"></a><span class="lineno">  256</span><span class="comment"> * Turn off the flag of semaphore then leaving critical section</span></div>
<div class="line"><a id="l00257" name="l00257"></a><span class="lineno">  257</span><span class="comment"> *</span></div>
<div class="line"><a id="l00258" name="l00258"></a><span class="lineno">  258</span><span class="comment"> * @param semid     semaphore identifier</span></div>
<div class="line"><a id="l00259" name="l00259"></a><span class="lineno">  259</span><span class="comment"> * @param semno     semaphore number</span></div>
<div class="line"><a id="l00260" name="l00260"></a><span class="lineno">  260</span><span class="comment"> *</span></div>
<div class="line"><a id="l00261" name="l00261"></a><span class="lineno">  261</span><span class="comment"> * @return true if successful, otherwise returns false</span></div>
<div class="line"><a id="l00262" name="l00262"></a><span class="lineno">  262</span><span class="comment"> */</span></div>
<div class="line"><a id="l00263" name="l00263"></a><span class="lineno"><a class="line" href="qsem_8c.html#a4904a3e477119a2cf177a23068a58fdd">  263</a></span><span class="keywordtype">bool</span> <a class="code hl_function" href="qsem_8c.html#a4904a3e477119a2cf177a23068a58fdd">qsem_leave</a>(<span class="keywordtype">int</span> semid, <span class="keywordtype">int</span> semno) {</div>
<div class="line"><a id="l00264" name="l00264"></a><span class="lineno">  264</span>    <span class="keyword">struct </span>sembuf sbuf;</div>
<div class="line"><a id="l00265" name="l00265"></a><span class="lineno">  265</span> </div>
<div class="line"><a id="l00266" name="l00266"></a><span class="lineno">  266</span>    <span class="comment">/* set sbuf */</span></div>
<div class="line"><a id="l00267" name="l00267"></a><span class="lineno">  267</span>    sbuf.sem_num = semno;</div>
<div class="line"><a id="l00268" name="l00268"></a><span class="lineno">  268</span>    sbuf.sem_op = 1;</div>
<div class="line"><a id="l00269" name="l00269"></a><span class="lineno">  269</span>    sbuf.sem_flg = SEM_UNDO;</div>
<div class="line"><a id="l00270" name="l00270"></a><span class="lineno">  270</span> </div>
<div class="line"><a id="l00271" name="l00271"></a><span class="lineno">  271</span>    <span class="comment">/* unlock */</span></div>
<div class="line"><a id="l00272" name="l00272"></a><span class="lineno">  272</span>    <span class="keywordflow">if</span> (semop(semid, &amp;sbuf, 1) != 0)</div>
<div class="line"><a id="l00273" name="l00273"></a><span class="lineno">  273</span>        <span class="keywordflow">return</span> <span class="keyword">false</span>;</div>
<div class="line"><a id="l00274" name="l00274"></a><span class="lineno">  274</span>    <span class="keywordflow">return</span> <span class="keyword">true</span>;</div>
<div class="line"><a id="l00275" name="l00275"></a><span class="lineno">  275</span>}</div>
<div class="line"><a id="l00276" name="l00276"></a><span class="lineno">  276</span><span class="comment"></span> </div>
<div class="line"><a id="l00277" name="l00277"></a><span class="lineno">  277</span><span class="comment">/**</span></div>
<div class="line"><a id="l00278" name="l00278"></a><span class="lineno">  278</span><span class="comment"> * Get the status of semaphore</span></div>
<div class="line"><a id="l00279" name="l00279"></a><span class="lineno">  279</span><span class="comment"> *</span></div>
<div class="line"><a id="l00280" name="l00280"></a><span class="lineno">  280</span><span class="comment"> * @param semid     semaphore identifier</span></div>
<div class="line"><a id="l00281" name="l00281"></a><span class="lineno">  281</span><span class="comment"> * @param semno     semaphore number</span></div>
<div class="line"><a id="l00282" name="l00282"></a><span class="lineno">  282</span><span class="comment"> *</span></div>
<div class="line"><a id="l00283" name="l00283"></a><span class="lineno">  283</span><span class="comment"> * @return true for the flag on, false for the flag off</span></div>
<div class="line"><a id="l00284" name="l00284"></a><span class="lineno">  284</span><span class="comment"> */</span></div>
<div class="line"><a id="l00285" name="l00285"></a><span class="lineno"><a class="line" href="qsem_8c.html#ac56cd066622f8e9bc669c70e51e8a378">  285</a></span><span class="keywordtype">bool</span> <a class="code hl_function" href="qsem_8c.html#ac56cd066622f8e9bc669c70e51e8a378">qsem_check</a>(<span class="keywordtype">int</span> semid, <span class="keywordtype">int</span> semno) {</div>
<div class="line"><a id="l00286" name="l00286"></a><span class="lineno">  286</span>    <span class="keywordflow">if</span> (semctl(semid, semno, GETVAL, 0) == 0)</div>
<div class="line"><a id="l00287" name="l00287"></a><span class="lineno">  287</span>        <span class="keywordflow">return</span> <span class="keyword">true</span>;  <span class="comment">// locked</span></div>
<div class="line"><a id="l00288" name="l00288"></a><span class="lineno">  288</span>    <span class="keywordflow">return</span> <span class="keyword">false</span>;  <span class="comment">// unlocked</span></div>
<div class="line"><a id="l00289" name="l00289"></a><span class="lineno">  289</span>}</div>
<div class="line"><a id="l00290" name="l00290"></a><span class="lineno">  290</span><span class="comment"></span> </div>
<div class="line"><a id="l00291" name="l00291"></a><span class="lineno">  291</span><span class="comment">/**</span></div>
<div class="line"><a id="l00292" name="l00292"></a><span class="lineno">  292</span><span class="comment"> * Release semaphore to system</span></div>
<div class="line"><a id="l00293" name="l00293"></a><span class="lineno">  293</span><span class="comment"> *</span></div>
<div class="line"><a id="l00294" name="l00294"></a><span class="lineno">  294</span><span class="comment"> * @param semid     semaphore identifier</span></div>
<div class="line"><a id="l00295" name="l00295"></a><span class="lineno">  295</span><span class="comment"> *</span></div>
<div class="line"><a id="l00296" name="l00296"></a><span class="lineno">  296</span><span class="comment"> * @return true if successful, otherwise returns false</span></div>
<div class="line"><a id="l00297" name="l00297"></a><span class="lineno">  297</span><span class="comment"> */</span></div>
<div class="line"><a id="l00298" name="l00298"></a><span class="lineno"><a class="line" href="qsem_8c.html#ab73d1cc1e7a82ce1b4b119ff56d25011">  298</a></span><span class="keywordtype">bool</span> <a class="code hl_function" href="qsem_8c.html#ab73d1cc1e7a82ce1b4b119ff56d25011">qsem_free</a>(<span class="keywordtype">int</span> semid) {</div>
<div class="line"><a id="l00299" name="l00299"></a><span class="lineno">  299</span>    <span class="keywordflow">if</span> (semid &lt; 0)</div>
<div class="line"><a id="l00300" name="l00300"></a><span class="lineno">  300</span>        <span class="keywordflow">return</span> <span class="keyword">false</span>;</div>
<div class="line"><a id="l00301" name="l00301"></a><span class="lineno">  301</span>    <span class="keywordflow">if</span> (semctl(semid, 0, IPC_RMID, 0) != 0)</div>
<div class="line"><a id="l00302" name="l00302"></a><span class="lineno">  302</span>        <span class="keywordflow">return</span> <span class="keyword">false</span>;</div>
<div class="line"><a id="l00303" name="l00303"></a><span class="lineno">  303</span>    <span class="keywordflow">return</span> <span class="keyword">true</span>;</div>
<div class="line"><a id="l00304" name="l00304"></a><span class="lineno">  304</span>}</div>
<div class="line"><a id="l00305" name="l00305"></a><span class="lineno">  305</span> </div>
<div class="line"><a id="l00306" name="l00306"></a><span class="lineno">  306</span><span class="preprocessor">#endif </span><span class="comment">/* DISABLE_IPC */</span><span class="preprocessor"></span></div>
<div class="ttc" id="aqsem_8c_html_a023df7733cebc81fc0aa0285772a914d"><div class="ttname"><a href="qsem_8c.html#a023df7733cebc81fc0aa0285772a914d">qsem_enter_force</a></div><div class="ttdeci">bool qsem_enter_force(int semid, int semno, int maxwaitms, bool *forceflag)</div><div class="ttdoc">Force to turn on the flag of semaphore.</div><div class="ttdef"><b>Definition</b> <a href="qsem_8c_source.html#l00232">qsem.c:232</a></div></div>
<div class="ttc" id="aqsem_8c_html_a4904a3e477119a2cf177a23068a58fdd"><div class="ttname"><a href="qsem_8c.html#a4904a3e477119a2cf177a23068a58fdd">qsem_leave</a></div><div class="ttdeci">bool qsem_leave(int semid, int semno)</div><div class="ttdoc">Turn off the flag of semaphore then leaving critical section.</div><div class="ttdef"><b>Definition</b> <a href="qsem_8c_source.html#l00263">qsem.c:263</a></div></div>
<div class="ttc" id="aqsem_8c_html_a5993822d89f9f6f36ffcedf95a921be0"><div class="ttname"><a href="qsem_8c.html#a5993822d89f9f6f36ffcedf95a921be0">qsem_enter_nowait</a></div><div class="ttdeci">bool qsem_enter_nowait(int semid, int semno)</div><div class="ttdoc">Try to turn on the flag of semaphore.</div><div class="ttdef"><b>Definition</b> <a href="qsem_8c_source.html#l00202">qsem.c:202</a></div></div>
<div class="ttc" id="aqsem_8c_html_aac470476fa8ecdc4cd9ec9596d3d6ca4"><div class="ttname"><a href="qsem_8c.html#aac470476fa8ecdc4cd9ec9596d3d6ca4">qsem_getid</a></div><div class="ttdeci">int qsem_getid(const char *keyfile, int keyid)</div><div class="ttdoc">Get semaphore identifier by keyfile and keyid for the existing semaphore.</div><div class="ttdef"><b>Definition</b> <a href="qsem_8c_source.html#l00155">qsem.c:155</a></div></div>
<div class="ttc" id="aqsem_8c_html_ab73d1cc1e7a82ce1b4b119ff56d25011"><div class="ttname"><a href="qsem_8c.html#ab73d1cc1e7a82ce1b4b119ff56d25011">qsem_free</a></div><div class="ttdeci">bool qsem_free(int semid)</div><div class="ttdoc">Release semaphore to system.</div><div class="ttdef"><b>Definition</b> <a href="qsem_8c_source.html#l00298">qsem.c:298</a></div></div>
<div class="ttc" id="aqsem_8c_html_ac56cd066622f8e9bc669c70e51e8a378"><div class="ttname"><a href="qsem_8c.html#ac56cd066622f8e9bc669c70e51e8a378">qsem_check</a></div><div class="ttdeci">bool qsem_check(int semid, int semno)</div><div class="ttdoc">Get the status of semaphore.</div><div class="ttdef"><b>Definition</b> <a href="qsem_8c_source.html#l00285">qsem.c:285</a></div></div>
<div class="ttc" id="aqsem_8c_html_ac66cb18076dd21f67ac4b9a5b246d2d2"><div class="ttname"><a href="qsem_8c.html#ac66cb18076dd21f67ac4b9a5b246d2d2">qsem_init</a></div><div class="ttdeci">int qsem_init(const char *keyfile, int keyid, int nsems, bool recreate)</div><div class="ttdoc">Initialize semaphore.</div><div class="ttdef"><b>Definition</b> <a href="qsem_8c_source.html#l00102">qsem.c:102</a></div></div>
<div class="ttc" id="aqsem_8c_html_acd893b0a1a6b390f27621ae0e93a5dd8"><div class="ttname"><a href="qsem_8c.html#acd893b0a1a6b390f27621ae0e93a5dd8">qsem_enter</a></div><div class="ttdeci">bool qsem_enter(int semid, int semno)</div><div class="ttdoc">Turn on the flag of semaphore then entering critical section.</div><div class="ttdef"><b>Definition</b> <a href="qsem_8c_source.html#l00180">qsem.c:180</a></div></div>
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